In Vitro Development of Bison Embryos Using Interspecies Somatic Cell Nuclear Transfer

Abstract

Interspecies somatic cell nuclear transfer (interspecies SCNT) has been explored in many domestic and non-domestic animal species. However, problems arise during the development of these embryos, which may be related to species-specific differences in nuclear-cytoplasmic communication. The objectives of this study were to investigate the possibility of producing bison embryos in vitro using interspecies SCNT and assess the developmental potential of these embryos. Treatment groups consisted of cattle in vitro fertilization (IVF) and cattle SCNT as controls and wood bison SCNT, plains bison SCNT and wisent SCNT as experimental groups. Cleavage and blastocyst rates were assessed, and blastocyst quality was determined using total cell number, apoptotic incidence and relative quantification of mitochondria-related genes NRF1, MT-CYB and TFAM. These results indicate that embryos can be produced by interspecies SCNT in all bison species/subspecies (13.34-33.54% blastocyst rates). Although increased incidence of apoptosis was observed in bison SCNT blastocysts compared to cattle SCNT controls (10.45-12.69 vs 8.76, respectively) that corresponded with significantly lower cell numbers (80-87 cells vs >100 cells, respectively), no major differences were observed in the expression of NRF1, MT-CYB and TFAM. This study is the first to report the production of bison embryos by interspecies SCNT. Blastocyst development in all three bison species/subspecies was greater than the rates obtained in previous studies by IVF, which supports the potential role of SCNT for in vitro embryo production in this species. Yet, further investigation of developmental competence and the factors influencing blastocyst quality and viability is required.

Supplement of autologous ooplasm into porcine somatic cell nuclear transfer embryos does not alter embryo development

“…The rates of SCNT blastocyst formation in bovine and mouse were more than 25% and were comparatively determined as higher efficiency than those of porcine SCNT (10%–17%) during in vitro pre‐implantation period. Furthermore, total cell number of porcine SCNT blastocysts consisted of 26–50 cells was generally lower than values from bovine or mouse SCNT blastocysts, which was more than 100 cells or approximately 60 cells, respectively (Chen et al., ; Costa‐Borges et al., ; Kumar et al., , ; Lee et al., ; Pan et al., ; Seaby et al., ). But in the present study, even after supplementing with autologous ooplasm into SCNT (AOT) embryos, no significant increases in the values of cleavage rate, blastocyst formation, hatched blastocyst and total cell number in comparison with SCNT embryos were observed.…”

“…It is generally addressed that the ratio of blastocyst formation in SCNT embryo during in vitro pre-implantation development is approximately 25%-33% in mouse and bovine, whereas that of porcine has still remained below 20% (Costa-Borges, Gonzalez, Santaló, & Ibáñez, 2011;Kumar et al, 2007;Lee et al, 2014;Pan et al, 2015;Seaby, Alexander, King, & Mastromonaco, 2013;Xu et al, 2013). As there have been considerable achievements of the application of OT, it can be possibly applied to porcine SCNT research to overcome low efficiency of embryo development.…”

Lack of effects of ooplasm transfer on early development of interspecies somatic cell nuclear transfer bison embryos

“…iSCNT studies have demonstrated the ability of enucleated oocytes to support first mitotic division with subsequent failure to activate embryonic genes [ 12 , 13 ]. In wild cattle iSCNT embryos, evidence of increased developmental arrest compared to SCNT controls was observed at the 8–16 cell stage (gaur: [ 14 ]; bison: [ 15 ]). Therefore, supplementing ooplasm from the same species as the somatic cell into iSCNT embryos could influence embryo development by transferring species-specific proteins, organelles, and other molecules [ 8 , 14 , 16 ].…”

“…Previous iSCNT experiments conducted in our laboratory used somatic cell donors from two North American bison subspecies ( Bison bison bison and Bison bison athabascae ) and domestic cattle oocytes to investigate potential causes responsible for embryonic arrest commonly observed at the 8–16 cell stage [ 15 , 19 ]. Numerous analyses performed at this stage of development showed alterations in mitochondrial function (metabolism, apoptosis, transcription) predominantly in bison iSCNT embryos [ 19 ].…”

CRYOBANKING OF SOMATIC CELLS IN CONSERVATION OF ANIMAL GENETIC RESOURCES: PROSPECTS AND SUCCESSES (review)

“…After the transfer of nuclei from sheep, pig, monkey or rat skin cells to MII enucleated cattle oocyte the cytoplast and xenogenic karyoplast joined. In further experiments cattle oocytes were used as cytoplasts in transfer of somatic cell nuclei of pigs (71), koala (72), antelope, goat (73), horses (74), black bear (75), mountain antelope (76), hens (77), yak and dog (78), and buffalo (79). These cytoplasts are preferable because of their low cost (due to isolation from ovaries of slaughtered animals) and easy cultivation which allows 90 % maturation.…”